Submitted by
Gard on Sat, 2003-11-08 03:29.
Quake 2
Partial Transparency in Quake 2 - Jex and Who
Something that's always been missing from Quake 2 is the ability to
have "holes" in a texture. Half-life was one of the first games to
properly implement "holes". Some examples of this are: see-through,
shoot-through railings made from a single brush, see-through grating for
floors. Well it is possible to do the same in Quake 2. While Quake 2's
Partial Texture Transparency is not perfect, when used intelligently, it
is a simple and effective way of adding detail without adding many
faces.
Image of the web texture before and after:
The first step in the process is preparing the texture; punching the
"holes" in it. Any part of the texture that will be invisible must be
coloured with Quake 2's transparency colour (Red: 159, Green: 91, Blue:
83). In our examples all the black spaces in the cobweb are replaced
with the transparency colour.
Once you've got you texture prepared, it is only a matter of
applying the texture to a brush and setting the proper flags. In all
cases either trans_33 or trans_66 will be checked (usually trans_66 as
trans_33 makes the visible parts of the texture very noticably
translucent) as this is what does the magic. This flag must be applied
to all faces of the brush. All other flags are completely optional as
with any other brush.

Image of the web texture without trans_66 checked.

Image of the web with trans_66 checked, the web texture is applied on all faces.

Image of the web with a totally clear texture, and the web texture applied to one face (the "correct" way).
When making a fence-like brush, you will only want to have 1 face of
the brush visible. One way would be to make a completely transparent
texture to apply to all faces but one. This would be the "proper" way to
do it. But there is also another trick which may come in handy as well
as decreasing the translucency of the visible fence. Create the fence as
a 1 unit thick brush. Keep the fence texture applied to both sides of
the brush. If the brush is any thicker than 1 unit the double effect can
become quite noticeable, but at 1 unit apart the player has to be very
close to notice the effect.

Image
of two fences, the right side is a brush 8 units thick. You can clearly
see the double effect. The fence on the right is only 1 unit thick,
making the double effect disappear, and also reducing the translucency.
One disadvantage of this technique is that it cannot be used in software mode:
Things to remember when using this technique:
This does not work in software rendering mode.
The visible parts of the texture will always be
translucent which makes thinner visible areas preferable (example: a
wire fence).
Translucency can be reduced by making the brush 1 unit thick with two exact visible sides overlapping eachother.
Placing the transparent brush partially out of range of
the player will reduce the chances of any translucency/double effect
being noticed.
Colour for transparency is: Red: 159, Green: 91, Blue: 83.
Detail added this way does not produce high r_speeds.
Only works with trans_33 or trans_66 applied to all faces.
Wherever the transparent brushes intersect other brushes, a faint red glow appears.
Some Examples:
You can download the example map here.
Making Rain
Entity Properties